Some of these churches, like the Orthodox Church, follow the Byzantine tradition, while others follow other liturgical traditions. The history of each Eastern Rite Catholic church is unique, some having sided with Rome at the time of the Great Schism and some being joined to Rome after that time.

They are sometimes referred to as Uniates, a term which many Eastern Catholics reject as derogatory, although it was historically used by both Eastern Catholics and the Latin hierarchy, as well.

Many of these churches have a direct non-Catholic (usually Orthodox or Oriental) counterpart. Others exist only within the Catholic Communion as they were either entirely received into communion with the Roman See or never left that communion.

History

Second Council of Lyons (1274)

Council of Ferrara-Florence (1439)

Union of Brest (1596)

Other Unions

Orientalium Ecclesiarum (Vatican II) and the Post-Council Period

Orientalium Ecclesiarium, the Decree on the Eastern Catholic Churches, was promulgated at the Second Vatican Council by Pope Paul VI on November 21, 1964. This decree instructs Eastern Catholics to "preserve their legitimate liturgical rite" and was in many ways a move away from previous episodes of open Latinizations. The Eastern liturgical traditions, at this time often heavily Latinized, was affirmed by the Council. In situations where the Eastern Tradition was lost, it was to be reclaimed. An example of this is the practice of infant Chrismation and communion and the singing of the Divine Office (i.e. Vespers and Matins) which, largely lost in many Eastern Catholic Churches, was slowly reclaimed after the council.

The rights and privileges of Eastern Catholic patriarchs were also emphasized in this document. The Synod as a form of government is given specific autonomous powers to, depending on the Church and territory in question, establish eparchies (dioceses) and exarchates, nominate and transfer bishops, and to legislate other items such as the date for Easter, appropriate liturgical texts, and the formation of clerics.

The document also discusses issues pertaining to the Orthodox Church. Eastern Christians are exhorted to recognize their role in ecumenism and to remain faithful to their liturgical traditions as an example. Eastern Orthodox clerics that enter into communion with the Roman See have recognized orders and are to be incorporated into their corresponding Eastern Catholic Church. (i.e. a Ukrainian Orthodox clergyman in Canada would be received into the Ukrainian Catholic Church and not into the Latin Church or another Eastern Catholic church) The document also controversially gives permission for Orthodox Christians to receive the sacraments in Catholic churches (Eastern or Western) without impediment.